Visual Basic > API and Miscellaneous

Create a timer using API calls

Create a timer using API calls

The following code can be used instead of a the VB timer control, to create a routine which is continuous called at a specified time interval:

Option Explicit

Private Declare Function SetTimer Lib "user32" (ByVal Hwnd As Long, ByVal nIDEvent As Long, ByVal uElapse As Long, ByVal lpTimerFunc As Long) As Long
Private Declare Function KillTimer Lib "user32" (ByVal Hwnd As Long, ByVal nIDEvent As Long) As Long
Private lTimerId As Long

'Purpose     :  Stops the timer routine
'Inputs      :  N/A
'Outputs     :  Returns True if the timer routine was stopped
'Notes       :
'Revisions   :

Function EndTimer() As Boolean
    If lTimerId Then
        lTimerId = KillTimer(0&, lTimerId)
        lTimerId = 0
        EndTimer = True
    End If
End Function

'Purpose     :  Starts the continuous calling of a private routine at a specific time interval.
'Inputs      :  lInterval           The interval (in ms) at which to call the routine
'Outputs     :  N/A
'Notes       :
'Revisions   :

Sub StartTimer(lInterval As Long)
    If lTimerId Then
        'End Current Timer
        EndTimer
    End If
    lTimerId = SetTimer(0&, 0&, ByVal lInterval, AddressOf TimerRoutine)
End Sub


'Purpose     :  Routine which is called repeatedly by the timer API.
'Inputs      :  Inputs are automatically generated.
'Outputs     :

'Notes       :
'Revisions   :

Private Sub TimerRoutine(ByVal lHwnd As Long, ByVal lMsg As Long, ByVal lIDEvent As Long, ByVal lTime As Long)
    'Place your code here...
End Sub